DSC measurements on experimental TGDDM/DDS resin systems: The influence of variations in resin composition and catalyst content

Abstract

As part of an international cooperation programme, DSC measurements were performed on 17 resin mixtures, of which the basic constituents were TGDDM and DGEBA epoxies and DDS hardener. The DDS/TGDDM and DGEBA/TGDDM ratios were systematically varied. In addition, for some of the mixtures small amounts of catalyst (0.2 and 2 weight percent) were added. The mixtures were cured in the DSC during a scan at constant heating rate (10 °C/min). From the results the reaction onset temperature, the peak temperature(s) and the heat of reaction were determined. A second DSC scan was performed to determine the glass transition temperatures of the cured resin systems. The results showed that the effect of the DDS/TGDDM ratio strongly depends on the catalyst content. By increasing the catalyst content, the curing reactions are shifted to lower temperatures and become less exothermic. The highest glass transition temperatures were measured for mixtures with 0.2 weight percent catalyst.